Hi Sonia,
Roles and responsibilities may vary from project to project.
However, you need to make sure the inbound partner profile in place for the IDoc type DOCMAS05 under PI logical system.
You can also try to post an inbound IDoc(WE19) with the mapping sheet for the interface and see if it works. You can take reference from one document posted through actual transaction by the functional owner.
If it is standard inbound processing, no customization(user exit enhancement) should be required.
Hope it helps!
Ambrish